The invention relates to a push-pull amplifier as described in the preamble of claim 1.
From the U.S. Pat. No. 5,805,020 a silent start Class D amplifier is known wherein start-up noise is corrected by adding an analog switch to the integrator circuit. In an alternate embodiment a silent start switch connects a variable resistance to a comparator input. The resistance gradually increases to overcome start-up noise.
A disadvantage of this known silent start Class D amplifier is that activating the switching unit is done at a completely arbitrary moment.
It is an object of the invention to provide a push-pull amplifier and a silent start circuit, which do not have the disadvantages of the known amplifier and silent start circuit. To this end, a push-pull amplifier comprises the features of claim 1. The invention provides the possibility to firstly bring the loop approximately at the required level and secondly to wait with the switching on moment till the moment at which the start up noise is as small as possible.
Embodiments of the invention are described in the dependent claims.
Herewith a cross-reference is made to the following co-pending applications of the same applicant and of the same date:
xe2x80x9cCarrousel handshakexe2x80x9d applicant""s ref. No. ID603908, application Ser. No. 0,201,818.2
xe2x80x9cLevel shifterxe2x80x9d applicant""s ref. No. ID604680, application Ser. No. 0,201,826.5
xe2x80x9cPWM limiterxe2x80x9d applicant""s ref. No. ID604682, application Ser. No. 0,201,828.1
xe2x80x9cDemodulation filterxe2x80x9d applicant""s ref. No. ID604683, application Ser. No. 0,201,829.9.